The invention relates to optical devices for measuring pressure or force with an electro-magnetic radiation source and a pressure membrane or a spring with a surface that at least partially reflects the electro-magnetic radiation of the electro-magnetic radiation source.
In DE 39 24 185 C1 (fiber optic pressure sensor), in DE 30 16 565 A1 (device for measuring and monitoring pressure within a limited, difficult to access space) and in EP 0 825 428 A2 (integrated optic-electronic combustion pressure sensor), the electro-magnetic radiation travels from, respectively, a radiation source via a light conductor cable to a pressure membrane and the reflected radiation travels via light conducting cable to photo detectors. The ends of the light-conducting cables are respectively arranged relative to the pressure membrane such that the exiting radiation fall onto the pressure membrane perpendicularly thereto. Moreover, the light-conducting cables terminate directly adjacent one another relative to the pressure membrane. In this manner, a portion of the reflected radiation travels, as a function of the deformation of the pressure membrane, to the ends of the light conducting cables, whereat such portion is branched in and further conducted to the photo detectors. The greater the deformation of the pressure membrane, the more diminished is the intensity of the radiation which reaches the photo detectors.
The disadvantage of the above-noted solutions is that, in particular, only a small portion of the reflected radiation is further conducted to the photo detectors. The sensitivity of the photo detectors consequently is substantially determinative of the measurement of the pressure against the pressure membrane. In particular, very small pressures or changes in pressure can only be measured to a limited extent.
The invention offers a solution to the problem of, on the one hand, so measuring the pressure of fluids or flow-capable substances in stationary and/or in flowing conditions that, as well, very small pressure deviations in fluid or in flow-capable substances can be captured or, on the other hand, in particular, to measure, in particular, small mechanical deformations on a spring caused by forces acting on the spring.